The Sonic Hedgehog-Gli pathway regulates dorsal brain growth and tumorigenesis

MYCN as an oncogene in pediatric brain tumors

MYCN, or N-Myc, is a member of the MYC family of transcription factors, which plays a key role in tumor formation by regulating genes involved in proliferation, differentiation, and apoptosis. MYCN is essential for neural development, especially for the appropriate growth and differentiation of neural progenitor cells, and its aberrant expression contributes to tumorigenesis. Gene amplification and mutations of this gene have been observed in a wide variety of cancer types, particularly in pediatric brain and non-brain tumors, such as neuroblastoma. Previous studies have provided extensive insights into the complex regulatory network of this transcription factor. Additionally, the presence of MYCN alterations in patient tumors serve as a key factor for risk stratification, as it correlates with poorer outcomes, and presents a significant challenge for treatment. Despite its clinical significance, therapeutic targeting of MYCN is challenging due to its structure, nuclear localization, and complex regulatory pathways. Efforts to target MYCN have focused on destabilizing the protein, modulating epigenetic mechanisms, and disrupting its transcriptional network. This review explores the role of MYCN in different subtypes of pediatric brain tumors and highlights novel ongoing therapeutic approaches. However, further research is necessary to develop more effective therapies and improve survival outcomes for patients with MYCN-driven tumor.

Epigenetic priming of neural progenitors by Notch enhances Sonic hedgehog signaling and establishes gliogenic competence

The remarkable cell diversity of multicellular organisms relies on the ability of multipotent progenitor cells to generate distinct cell types at the right times and locations during embryogenesis. A key question is how progenitors establish competence to respond to the different environmental signals required to produce specific cell types at critical developmental timepoints. We addressed this in the mouse developing forebrain, where neural progenitor cells must switch from producing neurons to making oligodendrocytes in response to increased Sonic Hedgehog (SHH) signaling during late embryogenesis. We show that progenitor responses to SHH are regulated by Notch signaling, thus permitting proper timing of the neuron-oligodendrocyte switch. Notch activity epigenetically primes genes associated with the oligodendrocyte lineage and SHH pathway, enabling amplified transcriptional responses to endogenous SHH and robust oligodendrogenesis. These results reveal a critical role for Notch in facilitating progenitor competence states and influencing cell fate transitions at the epigenetic level.

Histone-binding protein RBBP4 is necessary to promote neurogenesis in the developing mouse neocortical progenitors

Chromatin regulation plays a crucial role in neocortical neurogenesis, and mutations in chromatin modifiers are linked to neurodevelopmental disorders. RBBP4 is a core subunit of several chromatin-modifying complexes; however, its functional role and genome-wide occupancy profile in the neocortical primordium are unknown. To address this, we performed RBBP4 knockdown using CRISPR/Cas9 on neocortical progenitors derived from mice of both sexes at embryonic age 12.5 during deep-layer neurogenesis. Our study demonstrates that downregulation of RBBP4 in the E12.5 neocortical progenitors reduced neuronal output, specifically affecting CTIP2-expressing neurons. We demonstrate that RBBP4 plays an essential role in regulating neocortical progenitor proliferation. However, overexpression of RBBP4 alone was not sufficient to regulate neuronal fate.Genome-wide occupancy analysis revealed that RBBP4 primarily binds to distal regulatory elements, and neuron differentiation is a significant GO biological pathway of RBBP4-bound genes. Interestingly, we found that RBBP4 binds to Cdon, a receptor protein in the Shh signaling pathway, and knockdown of Cdon phenocopies RBBP4 knockdown resulting in a significant reduction in neurogenesis, particularly CTIP2-expressing neurons. CDON overexpression could rescue the phenotype caused upon loss of RBBP4 in the neocortex, thereby suggesting the functional link between RBBP4 and its target gene CDON. Our results shed light on the cellular role of RBBP4 and identify CDON as a novel regulator of deep-layer neurogenesis in the neocortical progenitors. Our findings are significant in the context of understanding how dysregulated chromatin regulation impacts cellular mechanisms in neurodevelopmental disorders.Significance Statement Chromatin modifier RBBP4 regulates chromatin structure and, thereby, gene expression. It is expressed in the dorsal telencephalon progenitors during deep-layer neurogenesis. In this study, we unveil a novel role for RBBP4 in regulating deep-layer neurogenesis in the neocortical progenitors. Our research underscores RBBP4's critical role in governing progenitor proliferation and neuronal subtype specification in the neocortex while identifying its genome-wide binding occupancy profile. Moreover, we identify Cdon as a novel binding target of RBBP4, also involved in regulating deep-layer neurogenesis. These findings illuminate the mechanisms by which chromatin modifiers influence neocortical development, offering insights into how mutations in chromatin modifiers could impact cortical development and contribute to neurodevelopmental disorders.

Sonic hedgehog signalling pathway in CNS tumours: its role and therapeutic implications

CNS tumours encompass a diverse group of neoplasms with significant morbidity and mortality. The SHH signalling pathway plays a critical role in the pathogenesis of several CNS tumours, including gliomas, medulloblastomas and others. By influencing cellular proliferation, differentiation and migration in CNS tumours, the SHH pathway has emerged as a promising target for therapeutic intervention. Current strategies such as vismodegib and sonidegib have shown efficacy in targeting SHH pathway activation. However, challenges such as resistance mechanisms and paradoxical effects observed in clinical settings underscore the complexity of effectively targeting this pathway. Advances in gene editing technologies, particularly CRISPR/Cas9, have provided valuable tools for studying SHH pathway biology, validating therapeutic targets and exploring novel treatment modalities. These innovations have paved the way for a better understanding of pathway dynamics and the development of more precise therapeutic interventions. In addition, the identification and validation of biomarkers of SHH pathway activation are critical to guide clinical decision making and improve patient outcomes. Molecular profiling and biomarker discovery efforts are critical steps towards personalised medicine approaches in the treatment of SHH pathway-associated CNS tumours. While significant progress has been made in understanding the role of the SHH pathway in CNS tumorigenesis, ongoing research is essential to overcome current therapeutic challenges and refine treatment strategies. The integration of molecular insights with advanced technologies and clinical expertise holds great promise for developing more effective and personalised therapies for patients with SHH pathway-driven CNS tumours.

Glioma-associated oncogene homolog 1 in breast invasive carcinoma: a comprehensive bioinformatic analysis and experimental validation

Background

Breast cancer, despite significant advancements in treatment, remains a major cause of cancer-related deaths among women. Immunotherapy, an emerging therapeutic strategy, offers promise for better outcomes, particularly through the modulation of immune functions. Glioma-Associated Oncogene Homolog 1 (GLI1), a transcription factor implicated in cancer biology, has shown varying roles in different cancers. However, its immunoregulatory functions in breast invasive carcinoma (BRCA) remain elusive. The current study aimed to unravel the expression patterns and immune-regulatory roles of GLI1 in BRCA.

Methods

Utilizing multiple bioinformatic platforms (TIMER2.0, GEPIA2, and R packages) based on The Cancer Genome Atlas (TCGA) and/or Genotype-Tissue Expression (GTEx) databases, we analyzed the expression of GLI1 in BRCA and its pan-cancer expression profiles. We further validated these findings by conducting qPCR and immunohistochemical staining on clinical BRCA samples. Kaplan-Meier analysis and Cox proportional hazards regression were performed to assess the prognostic value of GLI1. Additionally, the association between GLI1 expression and immune infiltration within the tumor immune microenvironment (TMIE) was examined.

Results

The findings reveal dysregulated expression of GLI1 in numerous cancers, with a significant decrease observed in BRCA. High GLI1 expression indicated better survival outcomes and was correlated with the age and stage of BRCA patients. GLI1 was involved in immune status, as evidenced by its strong correlations with immune and stromal scores and the infiltration levels of multiple immune cells. Meanwhile, GLI1 was co-expressed with multiple immune-related genes, and high GLI1 expression was associated with the activation of immune-related pathways, such as binding to proteasome and mismatch repair and retinol metabolism signaling pathways. Additionally, the differential expression of GLI1 may be related to the effect of immunotherapy on CTLA-4, PD-1, and other signals, and can effectively predict the immune efficacy.

Conclusion

Our study underscores the critical role of GLI1 in BRCA, both as a potential tumor suppressor and an immune regulator. The association between GLI1 expression and favorable prognosis suggests its potential as a prognostic biomarker and immunotherapeutic target in BRCA.

Molecular and cellular dynamics of the developing human neocortex at single-cell resolution

The development of the human neocortex is a highly dynamic process and involves complex cellular trajectories controlled by cell-type-specific gene regulation1. Here, we collected paired single-nucleus chromatin accessibility and transcriptome data from 38 human neocortical samples encompassing both the prefrontal cortex and primary visual cortex. These samples span five main developmental stages, ranging from the first trimester to adolescence. In parallel, we performed spatial transcriptomic analysis on a subset of the samples to illustrate spatial organization and intercellular communication. This atlas enables us to catalog cell type-, age-, and area-specific gene regulatory networks underlying neural differentiation. Moreover, combining single-cell profiling, progenitor purification, and lineage-tracing experiments, we have untangled the complex lineage relationships among progenitor subtypes during the transition from neurogenesis to gliogenesis in the human neocortex. We identified a tripotential intermediate progenitor subtype, termed Tri-IPC, responsible for the local production of GABAergic neurons, oligodendrocyte precursor cells, and astrocytes. Remarkably, most glioblastoma cells resemble Tri-IPCs at the transcriptomic level, suggesting that cancer cells hijack developmental processes to enhance growth and heterogeneity. Furthermore, by integrating our atlas data with large-scale GWAS data, we created a disease-risk map highlighting enriched ASD risk in second-trimester intratelencephalic projection neurons. Our study sheds light on the gene regulatory landscape and cellular dynamics of the developing human neocortex.

Numb positively regulates Hedgehog signaling at the ciliary pocket

Hedgehog (Hh) signaling relies on the primary cilium, a cell surface organelle that serves as a signaling hub for the cell. Using proximity labeling and quantitative proteomics, we identify Numb as a ciliary protein that positively regulates Hh signaling. Numb localizes to the ciliary pocket and acts as an endocytic adaptor to incorporate Ptch1 into clathrin-coated vesicles, thereby promoting Ptch1 exit from the cilium, a key step in Hh signaling activation. Numb loss impedes Sonic hedgehog (Shh)-induced Ptch1 exit from the cilium, resulting in reduced Hh signaling. Numb loss in spinal neural progenitors reduces Shh-induced differentiation into cell fates reliant on high Hh activity. Genetic ablation of Numb in the developing cerebellum impairs the proliferation of granule cell precursors, a Hh-dependent process, resulting in reduced cerebellar size. This study highlights Numb as a regulator of ciliary Ptch1 levels during Hh signal activation and demonstrates the key role of ciliary pocket-mediated endocytosis in cell signaling.

Hedgehog Signaling in Cortical Development

The Hedgehog (Hh) pathway plays a crucial role in embryonic development, acting both as a morphogenic signal that organizes tissue formation and a potent mitogenic signal driving cell proliferation. Dysregulated Hh signaling leads to various developmental defects in the brain. This article aims to review the roles of Hh signaling in the development of the neocortex in the mammalian brain, focusing on its regulation of neural progenitor proliferation and neuronal production. The review will summarize studies on genetic mouse models that have targeted different components of the Hh pathway, such as the ligand Shh, the receptor Ptch1, the GPCR-like transducer Smo, the intracellular transducer Sufu, and the three Gli transcription factors. As key insights into the Hh signaling transduction mechanism were obtained from mouse models displaying neural tube defects, this review will also cover some studies on Hh signaling in neural tube development. The results from these genetic mouse models suggest an intriguing hypothesis that elevated Hh signaling may play a role in the gyrification of the brain in certain species. Additionally, the distinctive production of GABAergic interneurons in the dorsal cortex in the human brain may also be linked to the extension of Hh signaling from the ventral to the dorsal brain region. Overall, these results suggest key roles of Hh signaling as both a morphogenic and mitogenic signal during the forebrain development and imply the potential involvement of Hh signaling in the evolutionary expansion of the neocortex.

Establishing Hedgehog Gradients during Neural Development

A morphogen is a signaling molecule that induces specific cellular responses depending on its local concentration. The concept of morphogenic gradients has been a central paradigm of developmental biology for decades. Sonic Hedgehog (Shh) is one of the most important morphogens that displays pleiotropic functions during embryonic development, ranging from neuronal patterning to axon guidance. It is commonly accepted that Shh is distributed in a gradient in several tissues from different origins during development; however, how these gradients are formed and maintained at the cellular and molecular levels is still the center of a great deal of research. In this review, we first explored all of the different sources of Shh during the development of the nervous system. Then, we detailed how these sources can distribute Shh in the surrounding tissues via a variety of mechanisms. Finally, we addressed how disrupting Shh distribution and gradients can induce severe neurodevelopmental disorders and cancers. Although the concept of gradient has been central in the field of neurodevelopment since the fifties, we also describe how contemporary leading-edge techniques, such as organoids, can revisit this classical model.

New insights intoCC2D2A-related Joubert syndrome

Purpose

In this study, we describe the phenotype and genotype of the largest cohort of patients with Joubert syndrome (JS) carrying pathogenic variants on one of the most frequent causative genes,CC2D2A.

Methods

We selected 53 patients with pathogenic variants onCC2D2A, compiled and analysed their clinical, neuroimaging and genetic information and compared it to previous literature.

Results

Developmental delay (motor and language) was nearly constant but patients had normal intellectual efficiency in 74% of cases (20/27 patients) and 68% followed mainstream schooling despite learning difficulties. Epilepsy was found in only 13% of cases. Only three patients had kidney cysts, only three had genuine retinal dystrophy and no subject had liver fibrosis or polydactyly. Brain MRIs showed typical signs of JS with rare additional features. Genotype–phenotype correlation findings demonstrate a homozygous truncating variant p.Arg950* linked to a more severe phenotype.

Conclusion

This study contradicts previous literature stating an association betweenCC2D2A-related JS and ventriculomegaly. Our study implies thatCC2D2A-related JS is linked to positive neurodevelopmental outcome and low rate of other organ defects except for homozygous pathogenic variant p.Arg950*. This information will help modulate patient follow-up and provide families with accurate genetic counselling.

Pax6 limits the competence of developing cerebral cortical cells to respond to inductive intercellular signals

The development of stable specialized cell types in multicellular organisms relies on mechanisms controlling inductive intercellular signals and the competence of cells to respond to such signals. In developing cerebral cortex, progenitors generate only glutamatergic excitatory neurons despite being exposed to signals with the potential to initiate the production of other neuronal types, suggesting that their competence is limited. Here, we tested the hypothesis that this limitation is due to their expression of transcription factor Pax6. We used bulk and single-cell RNAseq to show that conditional cortex-specific Pax6 deletion from the onset of cortical neurogenesis allowed some progenitors to generate abnormal lineages resembling those normally found outside the cortex. Analysis of selected gene expression showed that the changes occurred in specific spatiotemporal patterns. We then compared the responses of control and Pax6-deleted cortical cells to in vivo and in vitro manipulations of extracellular signals. We found that Pax6 loss increased cortical progenitors' competence to generate inappropriate lineages in response to extracellular factors normally present in developing cortex, including the morphogens Shh and Bmp4. Regional variation in the levels of these factors could explain spatiotemporal patterns of fate change following Pax6 deletion in vivo. We propose that Pax6's main role in developing cortical cells is to minimize the risk of their development being derailed by the potential side effects of morphogens engaged contemporaneously in other essential functions.

Fat3 regulates neural progenitor cells by promoting Yap activity during spinal cord development

Early embryonic development of the spinal cord requires tight coordination between proliferation of neural progenitors and their differentiation into distinct neuronal cell types to establish intricate neuronal circuits. The Hippo pathway is one of the well-known regulators to control cell proliferation and govern neural progenitor cell number, in which the downstream effector Yes-associated protein (Yap) promotes cell cycle progression. Here we show that an atypical cadherin Fat3, expressed highly in the neural tube, plays a critical role in maintaining proper number of proliferating progenitors. Knockdown of Fat3 in chick neural tube down-regulates expression of the proliferation markers but rather induces the expression of neural markers in the ventricular zone. We further show that deletion of Fat3 gene in mouse neural tube depletes neural progenitors, accompanied by neuronal gene expression in the ventral ventricular zone of the spinal cord. Finally, we found that Fat3 regulates the phosphorylation level of Lats1/2, the upstream kinase of Yap, resulting in dephosphorylation and stabilization of Yap, suggesting Yap as a key downstream effector of Fat3. Our study uncovers another layer of regulatory mechanisms in controlling the activity of Hippo signaling pathway to regulate the size of neural progenitor pools in the developing spinal cord.

Sonic Hedgehog Signaling in Cerebellar Development and Cancer

The sonic hedgehog (SHH) pathway regulates the development of the central nervous system in vertebrates. Aberrant regulation of SHH signaling pathways often causes neurodevelopmental diseases and brain tumors. In the cerebellum, SHH secreted by Purkinje cells is a potent mitogen for granule cell progenitors, which are the most abundant cell type in the mature brain. While a reduction in SHH signaling induces cerebellar structural abnormalities, such as hypoplasia in various genetic disorders, the constitutive activation of SHH signaling often induces medulloblastoma (MB), one of the most common pediatric malignant brain tumors. Based on the existing literature on canonical and non-canonical SHH signaling pathways, emerging basic and clinical studies are exploring novel therapeutic approaches for MB by targeting SHH signaling at distinct molecular levels. In this review, we discuss the present consensus on SHH signaling mechanisms, their roles in cerebellar development and tumorigenesis, and the recent advances in clinical trials for MB.

Hedgehog signaling plays a crucial role in hyperalgesia associated with neuropathic pain in mice

Neuropathic pain is a debilitating chronic syndrome of the nervous system caused by nerve injury. In Drosophila, the Hedgehog (Hh) signaling pathway is related to increased pain sensitivity (hyperalgesia) but does not affect the baseline nociceptive threshold. In general, the contribution of the Hh signaling pathway to neuropathic pain in vertebrates is a highly debated issue. Alternatively, we investigated the potential role of Hh signaling in mechanical allodynia using a mouse model of neuropathic pain. Seven days after spinal nerve-transection (SNT) surgery, microglial activation increased in the ipsilateral spinal dorsal horn compared with that in the sham group; however, 21 days after surgery, microglial activation decreased. Contrastingly, astrocyte activation in the spinal cord did not differ between the groups. On day 21 of postsurgery, the SNT group showed marked upregulation of sonic hedgehog expression in peripheral glial cells but not in dorsal root ganglion (DRG) neurons. Intrathecal administration of the Hh signaling inhibitor vismodegib attenuated the mechanical allodynia observed on day 21 postsurgery. Conversely, intrathecal treatment with the Hh signaling activator smoothened agonist in naive mice induced mechanical allodynia, which was abolished by the ATP transporter inhibitor clodronate. Moreover, inhibition of Hh signaling by pretreatment with vismodegib significantly reduced ATP secretion and the frequency/number of spontaneous elevations of intracellular calcium ion levels in cultured DRG cells. Thus, the Hh signaling pathway appears to modulate the neural activity of DRG neurons via ATP release, and it plays an important role in sustaining mechanical allodynia and hypersensitivity in a mouse model of neuropathic pain.

Impact of ABC Transporters in Osteosarcoma and Ewing's Sarcoma: Which Are Involved in Chemoresistance and Which Are Not?

The ATP-binding cassette (ABC) transporter superfamily consists of several proteins with a wide repertoire of functions. Under physiological conditions, ABC transporters are involved in cellular trafficking of hormones, lipids, ions, xenobiotics, and several other molecules, including a broad spectrum of chemical substrates and chemotherapeutic drugs. In cancers, ABC transporters have been intensely studied over the past decades, mostly for their involvement in the multidrug resistance (MDR) phenotype. This review provides an overview of ABC transporters, both related and unrelated to MDR, which have been studied in osteosarcoma and Ewing's sarcoma. Since different backbone drugs used in first-line or rescue chemotherapy for these two rare bone sarcomas are substrates of ABC transporters, this review particularly focused on studies that have provided findings that have been either translated to clinical practice or have indicated new candidate therapeutic targets; however, findings obtained from ABC transporters that were not directly involved in drug resistance were also discussed, in order to provide a more complete overview of the biological impacts of these molecules in osteosarcoma and Ewing's sarcoma. Finally, therapeutic strategies and agents aimed to circumvent ABC-mediated chemoresistance were discussed to provide future perspectives about possible treatment improvements of these neoplasms.

DLG5 variants are associated with multiple congenital anomalies including ciliopathy phenotypes

BACKGROUND

Cilia are dynamic cellular extensions that generate and sense signals to orchestrate proper development and tissue homeostasis. They rely on the underlying polarisation of cells to participate in signalling. Cilia dysfunction is a well-known cause of several diseases that affect multiple organ systems including the kidneys, brain, heart, respiratory tract, skeleton and retina.

METHODS

Among individuals from four unrelated families, we identified variants in discs large 5 (DLG5) that manifested in a variety of pathologies. In our proband, we also examined patient tissues. We depleted dlg5 in Xenopus tropicalis frog embryos to generate a loss-of-function model. Finally, we tested the pathogenicity of DLG5 patient variants through rescue experiments in the frog model.

RESULTS

Patients with variants of DLG5 were found to have a variety of phenotypes including cystic kidneys, nephrotic syndrome, hydrocephalus, limb abnormalities, congenital heart disease and craniofacial malformations. We also observed a loss of cilia in cystic kidney tissue of our proband. Knockdown of dlg5 in Xenopus embryos recapitulated many of these phenotypes and resulted in a loss of cilia in multiple tissues. Unlike introduction of wildtype DLG5 in frog embryos depleted of dlg5, introduction of DLG5 patient variants was largely ineffective in restoring proper ciliation and tissue morphology in the kidney and brain suggesting that the variants were indeed detrimental to function.

CONCLUSION

These findings in both patient tissues and Xenopus shed light on how mutations in DLG5 may lead to tissue-specific manifestations of disease. DLG5 is essential for cilia and many of the patient phenotypes are in the ciliopathy spectrum.

Biological Role of MYCN in Medulloblastoma: Novel Therapeutic Opportunities and Challenges Ahead

The constitutive and dysregulated expression of the transcription factor MYCN has a central role in the pathogenesis of the paediatric brain tumour medulloblastoma, with an increased expression of this oncogene correlating with a worse prognosis. Consequently, the genomic and functional alterations of MYCN represent a major therapeutic target to attenuate tumour growth in medulloblastoma. This review will provide a comprehensive synopsis of the biological role of MYCN and its family components, their interaction with distinct signalling pathways, and the implications of this network in medulloblastoma development. We will then summarise the current toolbox for targeting MYCN and highlight novel therapeutic avenues that have the potential to results in better-tailored clinical treatments.

The effects of hedgehog ligand neutralising antibody 5E1 in a mouse model of endometriosis

Objective

Endometriosis is a common and painful condition characterised by the formation of endometrial lesions within the peritoneal cavity. Previous studies have suggested a role for hedgehog signalling in the pathogenesis of endometriosis. We investigated the role of hedgehog signalling in the establishment of endometriosis lesions using 5E1, a hedgehog ligand neutralising antibody, and a mouse model of endometriosis. To mimic the initiation of endometriosis by retrograde menstruation, which is believed to occur in humans, donor mice underwent an artificial menstruation protocol. Fragments of menstrual endometrium were injected into the peritoneal cavity of estrogen primed recipients. Recipients received twice weekly injections of 5E1 or an isotype matched control antibody for three weeks. Lesions were collected and analysed for markers of epithelium, proliferation and apoptosis by immunofluorescence microscopy.

Results

Treatment with 5E1 reduced the number of lesions found on the mesentery. No significant changes were found in the size of lesions, abundance of endometrial epithelial cells, proliferation or apoptosis.

The use of hedgehog antagonists in cancer therapy: a comparison of clinical outcomes and gene expression analyses

Hedgehog (HH) signaling, a critical developmental pathway, has been implicated in cancer initiation and progression. With vismodegib and sonidegib having been approved for clinical use, increasing numbers of HH inhibitors alone and in combination with chemotherapies are in clinical trials. Here we highlight the clinical research on HH antagonists and the genetics of response to these compounds in human cancers. Selectivity of HH inhibitors, determined by decreased pathway transcriptional activity, has been demonstrated in many clinical trials. Patients with advanced/metastatic basal cell carcinoma have benefited the most, whereas HH antagonists did little to improve survival rates in other cancers. Correlation between clinical response and HH gene expression vary among different cancer types. Predicting response and resistance to HH inhibitors presents a challenge and continues to remain an important area of research. New approaches combine standard of care chemotherapies and molecularly targeted therapies to increase the clinical utility of HH inhibitors.

Extracellular Nanomatrix-Induced Self-Organization of Neural Stem Cells into Miniature Substantia Nigra-Like Structures with Therapeutic Effects on Parkinsonian Rats

Substantia nigra (SN) is a complex and critical region of the brain wherein Parkinson's disease (PD) arises from the degeneration of dopaminergic neurons. Miniature SN-like structures (mini-SNLSs) constructed from novel combination of nanomaterials and cell technologies exhibit promise as potentially curative cell therapies for PD. In this work, a rapid self-organization of mini-SNLS, with an organizational structure and neuronal identities similar to those of the SN in vivo, is achieved by differentiating neural stem cells in vitro on biocompatible silica nanozigzags (NZs) sculptured by glancing angle deposition, without traditional chemical growth factors. The differentiated neurons exhibit electrophysiological activity in vitro. Diverse physical cues and signaling pathways that are determined by the nanomatrices and lead to the self-organization of the mini-SNLSs are clarified and elucidated. In vivo, transplantation of the neurons from a mini-SNLS results in an early and progressive amelioration of PD in rats. The sculptured medical device reported here enables the rapid and specific self-organization of region-specific and functional brain-like structures without an undesirable prognosis. This development provides promising and significant insights into the screening of potentially curative drugs and cell therapies for PD.

Negative Regulation of mTOR Signaling Restricts Cell Proliferation in the Floor Plate

The neural tube is composed of a number of neural progenitors and postmitotic neurons distributed in a quantitatively and spatially precise manner. The floor plate, located in the ventral-most region of the neural tube, has a lot of unique characteristics, including a low cell proliferation rate. The mechanisms by which this region-specific proliferation rate is regulated remain elusive. Here we show that the activity of the mTOR signaling pathway, which regulates the proliferation of the neural progenitor cells, is significantly lower in the floor plate than in other domains of the embryonic neural tube. We identified the forkhead-type transcription factor FoxA2 as a negative regulator of mTOR signaling in the floor plate, and showed that FoxA2 transcriptionally induces the expression of the E3 ubiquitin ligase RNF152, which together with its substrate RagA, regulates cell proliferation via the mTOR pathway. Silencing of RNF152 led to the aberrant upregulation of the mTOR signal and aberrant cell division in the floor plate. Taken together, the present findings suggest that floor plate cell number is controlled by the negative regulation of mTOR signaling through the activity of FoxA2 and its downstream effector RNF152.

TGLI1 transcription factor mediates breast cancer brain metastasis via activating metastasis-initiating cancer stem cells and astrocytes in the tumor microenvironment

Mechanisms for breast cancer metastasis remain unclear. Whether truncated glioma-associated oncogene homolog 1 (TGLI1), a transcription factor known to promote angiogenesis, migration and invasion, plays any role in metastasis of any tumor type has never been investigated. In this study, results of two mouse models of breast cancer metastasis showed that ectopic expression of TGLI1, but not GLI1, promoted preferential metastasis to the brain. Conversely, selective TGLI1 knockdown using antisense oligonucleotides led to decreased breast cancer brain metastasis (BCBM) in vivo. Immunohistochemical staining showed that TGLI1, but not GLI1, was increased in lymph node metastases compared to matched primary tumors, and that TGLI1 was expressed at higher levels in BCBM specimens compared to primary tumors. TGLI1 activation is associated with a shortened time to develop BCBM and enriched in HER2-enriched and triple-negative breast cancers. Radioresistant BCBM cell lines and specimens expressed higher levels of TGLI1, but not GLI1, than radiosensitive counterparts. Since cancer stem cells (CSCs) are radioresistant and metastasis-initiating cells, we examined TGLI1 for its involvement in breast CSCs and found TGLI1 to transcriptionally activate stemness genes CD44, Nanog, Sox2, and OCT4 leading to CSC renewal, and TGLI1 outcompetes with GLI1 for binding to target promoters. We next examined whether astrocyte-priming underlies TGLI1-mediated brain tropism and found that TGLI1-positive CSCs strongly activated and interacted with astrocytes in vitro and in vivo. These findings demonstrate, for the first time, that TGLI1 mediates breast cancer metastasis to the brain, in part, through promoting metastasis-initiating CSCs and activating astrocytes in BCBM microenvironment.

FAT1 cadherin controls neuritogenesis during NTera2 cell differentiation

Fat1 cadherin is broadly expressed throughout the nervous system and has been implicated in neuronal differentiation. Here we examined the functional contribution of FAT1 during neuronal differentiation of the Ntera2 cell line model. FAT1 expression was increased during the retinoic acid (RA)-induced differentiation of NTera2 cells. Depletion of FAT1 with siRNA decreased the number of neurites produced after RA treatment. Moreover, FAT1 silencing also led to decreased Ser127-phosphorylation of YAP along with transcriptional increases in the Hippo target genes CTGF and ANKRD1, suggesting FAT1 alters Hippo signalling during differentiation. In the context of the Ntera2 model, FAT1 is required for efficient neuritogenesis, acting as a regulator of neurite formation during the early stages of differentiation.

Promyelocytic leukemia zinc finger is involved in the formation of deep layer cortical neurons

BACKGROUND

Promyelocytic leukemia zinc finger (Plzf), a transcriptional regulator involved in a lot of important biological processes during development, has been implied to maintain neural stem cells and inhibit their differentiation into neurons. However, the effects of Plzf on brain structures and functions are still not clarified.

RESULTS

We showed that Plzf expression was detected as early as embryonic day (E) 9.5 in Pax6⁺ cells in the mouse brain, and was completely disappeared in telencephalon before the initiation of cortical neurogenesis. Loss of Plzf resulted in a smaller cerebral cortex with a decrease in the number of Tbr1⁺ deep layer neurons due to a decrease of mitotic cell number in the ventricular zone of forebrain at early developmental stage. Microarray, qRT-PCR, and flow cytometry analysis identified dysregulation of Mash1 proneural gene expression. We also observed an impairment of recognition memory in Plzf-deficient mice.

CONCLUSIONS

Plzf is expressed at early stages of brain development and involved in the formation of deep layer cortical neurons. Loss of Plzf results in dysregulation of Mash1, microcephaly with reduced numbers of early-born neurons, and impairment of recognition memory.

Emerging Roles of Primary Cilia in Glioma

Primary cilia are microtubule-based organelles that are typically present on cells during the G0 or G1-S/G2 phases of the cell cycle. Recent studies of glioblastoma (GBM) biopsies, a brain tumor that is notorious for its aggressive growth and resistance to treatment, show that many cells in the tumor lack cilia. At this point, it remains unclear whether primary cilia promote or suppress glioma tumorigenesis. In this review, we will discuss the different roles that have been proposed for primary cilia in glioma and how cilia may contribute to the resistance of these tumors to current therapies.

Structural Simplification of Natural Products

Natural products (NPs) are important sources of clinical drugs due to their structural diversity and biological prevalidation. However, the structural complexity of NPs leads to synthetic difficulties, unfavorable pharmacokinetic profiles, and poor drug-likeness. Structural simplification by truncating unnecessary substructures is a powerful strategy for overcoming these limitations and improving the efficiency and success rate of NP-based drug development. Herein, we will provide a comprehensive review of the structural simplification of NPs with a focus on design strategies, case studies, and new technologies. In particular, a number of successful examples leading to marketed drugs or drug candidates will be discussed in detail to illustrate how structural simplification is applied in lead optimization of NPs.

Abnormal activity of transcription factors gli in high-grade gliomas

Malignant transformation is associated with loss of cell differentiation, anaplasia. Transcription factors gli, required for embryonic development, may be involved in this process. We studied the activity of transcription factors gli in high-grade gliomas and their role in maintenance of stem cell state and glioma cell survival. 20 glioma cell lines and a sample of a normal adult brain tissue were used in the present study. We found the expression of gli target genes, including GLI1 and FOXM1, in all tested glioma cell lines, but not in the normal tissue. Interestingly, the expression of gli target genes in some glioma cell lines was observed together with a high level of their transcriptional repressor, Gli3R. Knockdown of GLI3 in one of these lines resulted in decrease of gli target gene expression. These data suggest that Gli3R does not prevent the gli target genes transcription, and gli3 acts in glioma cells more as an activator, than a repressor of transcription. We observed that gli regulated the expression of such genes, as SOX2 or OCT4 that maintain stem cell state, and TET1, involving in DNA demethylation. Treatment with GANT61 or siRNA against GLI1, GLI2, or GLI3 could result in complete glioma cell death, while cyclopamine had a weaker and line-specific effect on glioma cell survival. Thus, the gli transcription factors are abnormally active in high-grade gliomas, regulate expression of genes, maintaining the stem cell state, and contribute to glioma cell survival.

Identification of CD24 as a marker of Patched1 deleted medulloblastoma-initiating neural progenitor cells

High morbidity and mortality are common traits of malignant tumours and identification of the cells responsible is a focus of on-going research. Many studies are now reporting the use of antibodies specific to Clusters of Differentiation (CD) cell surface antigens to identify tumour-initiating cell (TIC) populations in neural tumours. Medulloblastoma is one of the most common malignant brain tumours in children and despite a considerable amount of research investigating this tumour, the identity of the TICs, and the means by which such cells can be targeted remain largely unknown. Current prognostication and stratification of medulloblastoma using clinical factors, histology and genetic profiling have classified this tumour into four main subgroups: WNT, Sonic hedgehog (SHH), Group 3 and Group 4. Of these subgroups, SHH remains one of the most studied tumour groups due to the ability to model medulloblastoma formation through targeted deletion of the Shh pathway inhibitor Patched1 (Ptch1). Here we sought to utilise CD antibody expression to identify and isolate TIC populations in Ptch1 deleted medulloblastoma, and determine if these antibodies can help classify the identity of human medulloblastoma subgroups. Using a fluorescence-activated cell sorted (FACS) CD antibody panel, we identified CD24 as a marker of TICs in Ptch1 deleted medulloblastoma. CD24 expression was not correlated with markers of astrocytes or oligodendrocytes, but co-labelled with markers of neural progenitor cells. In conjunction with CD15, proliferating CD24+/CD15+ granule cell precursors (GCPs) were identified as a TIC population in Ptch1 deleted medulloblastoma. On human medulloblastoma, CD24 was found to be highly expressed on Group 3, Group 4 and SHH subgroups compared with the WNT subgroup, which was predominantly positive for CD15, suggesting CD24 is an important marker of non-WNT medulloblastoma initiating cells and a potential therapeutic target in human medulloblastoma. This study reports the use of CD24 and CD15 to isolate a GCP-like TIC population in Ptch1 deleted medulloblastoma, and suggests CD24 expression as a marker to help stratify human WNT tumours from other medulloblastoma subgroups.

Sonic Hedgehog Signaling Rises to the Surface: Emerging Roles in Neocortical Development

The mammalian neocortex is composed of a diverse population of neuronal and glial cells that are crucial for cognition and consciousness. Orchestration of molecular events that lead to the production of distinct cell lineages is now a major research focus. Recent studies in mammalian animal models reveal that Sonic Hedgehog (Shh) signaling plays crucial roles in this process. In this review, we will evaluate these studies and provide insights on how Shh signaling specifically influence cortical development, beyond its established roles in telencephalic patterning, by specifically focusing on its impact on cells derived from the cortical radial glial (RG) cells. We will also assess how these findings further advance our knowledge of neurological diseases and discuss potential roles of targeting Shh signaling in therapies.

Activity of Metabotropic Glutamate Receptor 4 Suppresses Proliferation and Promotes Apoptosis With Inhibition of Gli-1 in Human Glioblastoma Cells

Glioblastoma multiforme (GBM) is the most lethal glioma variant in the adult brain and among the deadliest of human cancers. Increasing evidence has shown that metabotropic glutamate receptor subtype 4 (mGluR4) expression may play roles in regulating the growth of neural stem cells as well as several cancer cell lines. Here, we investigated the effects of mGluR4 on the growth and apoptosis of the LN229 GBM cell line. Involvement of Gli-1, one of the key transcription factors in the sonic Hedgehog (SHH) signaling pathway, was further explored. In this study, mGluR4 was activated using selective agonist VU0155041; and gene-targeted siRNAs were used to generate loss of function of mGluR4 and Gli-1 in LN229 cells. The results demonstrated that LN229 cells expressed mGluR4 and the agonist VU0155041 decreased cell viability in a dose- and time-dependent manner. Activation of mGluR4 inhibited cyclin D1 expression, activated pro-caspase-8/9/3, and disrupted the balance of Bcl-2/Bax expression, which indicated cell cycle arrest and apoptosis of LN229 cells, respectively. Furthermore, Gli-1 expression was reduced by mGluR4 activation in LN229 cells, and downregulation of Gli-1 expression by gene-targeted siRNA resulted in both inhibition of cell proliferation and promotion of apoptosis. Moreover, VU0155041 treatment substantially blocked SHH-induced cyclin D1 expression and cell proliferation, while increasing TUNEL-positive cells and the activation of apoptosis-related proteins. We concluded that activation of mGluR4 expressed in LN229 cells could inhibit GBM cell growth by decreasing cell proliferation and promoting apoptosis. Further suppression of intracellular Gli-1 expression might be involved in the action of mGluR4 on cancer cells. Our study suggested a novel role of mGluR4, which might serve as a potential drug target for control of GBM cell growth.

Interaction between STAT3 and GLI1/tGLI1 oncogenic transcription factors promotes the aggressiveness of triple-negative breast cancers and HER2-enriched breast cancer

Signal transducer and activator of transcription 3 (STAT3), glioma oncogene homolog 1 (GLI1), and truncated GLI1 (tGLI1) are oncogenic transcription factors playing important roles in breast cancer. tGLI1 is a gain-of-function GLI1 isoform. Whether STAT3 physically and/or functionally interacts with GLI1/tGLI1 has not been explored. To address this knowledge gap, we analyzed 47 node-positive breast cancer specimens using immunohistochemical staining and found that phosphorylated-STAT3 (Y705), GLI1, and tGLI1 are co-overexpressed in the majority of triple-negative breast carcinomas (64%) and HER2-enriched (68%) breast carcinomas, and in lymph node metastases (65%). Using gene set enrichment analysis, we analyzed 710 breast tumors and found that STAT3 activation and GLI1/tGLI1 activation signatures are co-enriched in triple-negative subtypes of breast cancers and HER2-enriched subtypes of breast cancers, but not in luminal subtypes of breast cancers. Patients with high levels of STAT3 and GLI1/tGLI1 co-activation in their breast tumors had worse metastasis-free survival compared to those with low levels. Since these proteins co-overexpress in breast tumors, we examined whether they form complexes and observed that STAT3 interacted with both GLI1 and tGLI1. We further found that the STAT3-GLI1 and STAT3-tGLI1 complexes bind to both consensus GLI1-binding and STAT3-binding sites using chromatin immunoprecipitation (ChIP) assay, and that the co-overexpression markedly activated a promoter controlled by GLI1-binding sites. To identify genes that can be directly co-activated by STAT3 and GLI1/tGLI1, we analyzed three ChIP-seq datasets and identified 34 potential target genes. Following validations using reverse transcription polymerase chain reaction and survival analysis, we identified three genes as novel transcriptional targets of STAT3 and GLI1/tGLI1, R-Ras2, Cep70, and UPF3A. Finally, we observed that co-overexpression of STAT3 with GLI1/tGLI1 promoted the ability of breast cancer cells to form mammospheres and that STAT3 only cooperates with tGLI1 in immortalized mammary epithelial cells. In summary, our study identified novel physical and functional cooperation between two families of oncogenic transcription factors, and the interaction contributes to aggressiveness of breast cancer cells and poor prognosis of triple-negative breast cancers and HER2-enriched breast cancers.

Nonhistone targets of KAT2A and KAT2B implicated in cancer biology 1

Lysine acetylation is a critical post-translation modification that can impact a protein's localization, stability, and function. Originally thought to only occur on histones, we now know thousands of nonhistone proteins are also acetylated. In conjunction with many other proteins, lysine acetyltransferases (KATs) are incorporated into large protein complexes that carry out these modifications. In this review we focus on the contribution of two KATs, KAT2A and KAT2B, and their potential roles in the development and progression of cancer. Systems biology demands that we take a broad look at protein function rather than focusing on individual pathways or targets. As such, in this review we examine KAT2A/2B-directed nonhistone protein acetylations in cancer in the context of the 10 "Hallmarks of Cancer", as defined by Hanahan and Weinberg. By focusing on specific examples of KAT2A/2B-directed acetylations with well-defined mechanisms or strong links to a cancer phenotype, we aim to reinforce the complex role that these enzymes play in cancer biology.

Multiple roles of Sonic Hedgehog in the developing human cortex are suggested by its widespread distribution

Sonic Hedgehog (Shh) plays an instrumental role in brain development, fine-tuning processes such as cell proliferation, patterning, and fate specification. Although, mutations in the SHH pathway in humans are associated with various neurodevelopmental disorders, ranging from holoprosencephaly to schizophrenia, its expression pattern in the developing human brain is not well established. We now determined the previously not reported wide expression of SHH in the human fetal cerebral cortex during most of the gestation period (10–40 gestational weeks). This spatiotemporal distribution puts Shh in a position to influence the fundamental processes involved in corticogenesis. SHH expression increased during development, shifting from progenitor cells in the proliferative zones to neurons, both glutamatergic and GABAergic, and astrocytes in upper cortical compartments. Importantly, the expression of its downstream effectors and complementary receptors revealed evolutionary differences in SHH-pathway gene expression between humans and rodents.

Sonic hedgehog antagonists reduce size and alter patterning of the frog inner ear

Sonic hedgehog (Shh) signaling plays a major role in vertebrate development, from regulation of proliferation to the patterning of various organs. In amniotes, Shh affects dorsoventral patterning in the inner ear but affects anteroposterior patterning in teleost ears. It remains unknown how altered function of Shh relates to morphogenetic changes that coincide with the evolution of limbs and novel auditory organs in the ear. In this study, we used the tetrapod, Xenopus laevis, to test how increasing concentrations of the Shh signal pathway antagonist, Vismodegib, affects ear development. Vismodegib treatment dose dependently alters the development of the ear, hypaxial muscle, and indirectly the Mauthner cell through its interaction with the inner ear afferents. Together, these phenotypes have an effect on escape response. The altered Mauthner cell likely contributes to the increased time to respond to a stimulus. In addition, the increased hypaxial muscle in the trunk likely contributes to the subtle change in animal C-start flexion angle. In the ear, Vismodegib treatment results in decreasing segregation between the gravistatic sensory epithelia as the concentration of Vismodegib increases. Furthermore, at higher doses, there is a loss of the horizontal canal but no enantiomorphic transformation, as in bony fish lacking Shh. Like in amniotes, Shh signaling in frogs affects dorsoventral patterning in the ear, suggesting that auditory sensory evolution in sarcopterygians/tetrapods evolved with a shift of Shh function in axis specification. © 2017 Wiley Periodicals, Inc. Develop Neurobiol 77: 1385-1400, 2017.

Inhibition of sonic hedgehog signaling blocks cell migration and growth but induces apoptosis via suppression of FOXQ1 in natural killer/T-cell lymphoma

The present study explored the effects of Forkhead box Q1 (FOXQ1) on cell proliferation, cell cycle and apoptosis via the Sonic hedgehog (Shh) pathway in Natural killer/T-cell lymphoma (NKTCL). Quantitative real time-polymerase chain reaction (qRT-PCR) was performed to detect FOXQ1 expression in 117 NKTCL patients and 120 healthy controls. Additionally, FOXQ1 expression in NKTCL cell lines (HANK-1, NK-92, SNK-6, SNT-8 and YT) was determined by western blotting and qRT-PCR. SNK-6 cells were transfected with FOXQ1-shRNA or Shh pathway inhibitor Cyclopamine/recombinant protein Shh. Cell counting kit-8 (CCK-8) and 5-bromo-2-deoxy-uridine (BrdU) incorporation assays were conducted to detect cell proliferation, flow cytometry was used to determine the cell cycle and cell apoptosis, and western blotting was used to detect protein expression. FOXQ1 expression was higher in NKTCL patients than in healthy controls, which was related to Ann Arbor stage, bone marrow involvement and the 5year survival rate in NKTCL patients. Moreover, FOXQ1 expression, pathological type, Ann Arbor stage, B symptom and bone marrow involvement were independent risk factors in NKTCL. Shh pathway-related proteins were down-regulated after transfection of SNK-6 cells with FOXQ1-shRNA. Additionally, SNK-6 cell proliferation was greatly reduced, the cell cycle was blocked at the G0/G1 phase, and the expression of CyclinD1 and CyclinE was markedly decreased, while an increase in cell apoptosis with elevated Bcl-2-associated X protein (Bax) and Caspase-3 and reduced B-cell lymphoma/leukemia-2 (Bcl-2) were also observed. However, no significant alterations were observed between the FOXQ1-shRNA+Shh and Blank groups. The inhibition of FOXQ1 restricted NKTCL cell proliferation and growth but induced apoptosis via blocking the Shh signaling pathway.

Stimulation of IL-1β and IL-6 through NF-κB and sonic hedgehog-dependent pathways in mouse astrocytes by excretory/secretory products of fifth-stage larval Angiostrongylus cantonensis

BACKGROUND

Angiostrongylus cantonensis is an important causative agent of eosinophilic meningitis and eosinophilic meningoencephalitis in humans. Previous studies have shown that the Sonic hedgehog (Shh) signaling pathway may reduce cell apoptosis by inhibiting oxidative stress in A. cantonensis infection. In this study, we investigated the relationship between cytokine secretion and Shh pathway activation after treatment with excretory/secretory products (ESP) of fifth-stage larval A. cantonensis (L5).

RESULTS

The results showed that IL-1β and IL-6 levels in mouse astrocytes were increased. Moreover, ESP stimulated the protein expression of Shh pathway molecules, including Shh, Ptch, Smo and Gli-1, and induced IL-1β and IL-6 secretion. The transcription factor nuclear factor-κB (NF-κB) plays an important role in inflammation, and it regulates the expression of proinflammatory genes, including cytokines and chemokines, such as IL-1β and TNF-α. After ESP treatment, NF-κB induced IL-1β and IL-6 secretion in astrocytes by activating the Shh signaling pathway.

CONCLUSIONS

Overall, the data presented in this study showed that ESP of fifth-stage larval A. cantonensis stimulates astrocyte activation and cytokine generation through NF-κB and the Shh signaling pathway.

Nucleolar and spindle associated protein 1 promotes the aggressiveness of astrocytoma by activating the Hedgehog signaling pathway

BACKGROUND

The prognosis of human astrocytoma is poor, and the molecular alterations underlying its pathogenesis still needed to be elucidated. Nucleolar and spindle associated protein 1 (NUSAP1) was observed in several types of cancers, but its role in astrocytoma remained unknown.

METHODS

The expression of NUSAP1 in astrocytoma cell lines and tissues were measured with western blotting and Real-Time PCR. Two hundred and twenty-one astrocytoma tissue samples were analyzed by immunochemistry to demonstrate the correlation between the NUSAP1 expression and clinicopathological characteristics. 3-(4,5-dimethylthiazol-2-yl) 2,5-diphenyltetrazolium bromide (MTT) assay, colony formation, transwell matrix penetration assay, wound healing assay and anchorage-independent growth assay were used to investigate the biological effect of NUSAP1 in astrocytoma. An intracranial brain xenograft tumor model was used to confirm the oncogenic role of NUSAP1 in human astrocytoma. Luciferase reporter assay was used to investigate the effect of NUSAP1 on Hedgehog signaling pathway.

RESULTS

NUSAP1 was markedly overexpressed in astrocytoma cell lines and tissues compared with normal astrocytes and brain tissues. NUSAP1 was found to be overexpressed in 152 of 221 (68.78%) astrocytoma tissues, and was significantly correlated to poor survival. Further, ectopic expression or knockdown of NUSAP1 significantly promoted or inhibited, respectively, the invasive ability of astrocytoma cells. Moreover, intracranial xenografts of astrocytoma cells engineered to express NUSAP1 were highly invasive compared with the parental cells. With regard to its molecular mechanism, upregulation of NUSAP1 in astrocytoma cells promoted the nuclear translocation of GLI family zinc finger 1 (GLI1) and upregulated the downstream genes of the Hedgehog pathway.

CONCLUSION

These findings indicate that NUSAP1 contributes to the progression of astrocytoma by enhancing tumor cell invasiveness via activation of the Hedgehog signaling pathway, and that NUSAP1 might be a potential prognostic biomarker as well as a target in astrocytoma.

The Hedgehog-GLI pathway in embryonic development and cancer: implications for pulmonary oncology therapy

Transcriptional regulation and epigenetic mechanisms closely control gene expression through diverse physiological and pathophysiological processes. These include the development of germ layers and post-natal epithelial cell-tissue differentiation, as well as, involved with the induction, promotion and/or progression of human malignancies. Diverse studies have shed light on the molecular similarities and differences involved in the stages of embryological epithelial development and dedifferentiation processes in malignant tumors of epithelial origin, of which many focus on lung carcinomas. In lung cancer, several transcriptional, epigenetic and genetic aberrations have been described to partly arise from environmental risk factors, but ethnic genetic predisposition factors may also play a role. The classification of the molecular hallmarks of cancer has been essential to study and achieve a comprehensive view of the interaction networks between cell signaling pathways and functional roles of the transcriptional and epigenetic regulatory mechanisms. This has in turn increased understanding on how these molecular networks are involved in embryo-layers and malignant diseases development. Ultimately, a major biomedicine goal is to achieve a thorough understanding of their roles as diagnostic, prognostic and treatment response indicators in lung oncological patients. Recently, several notable cell-signaling pathways have been studied based on their contribution to promoting and/or regulating the engagement of different cancer hallmarks, among them genome instability, exacerbated proliferative signaling, replicative immortality, tumor invasion-metastasis, inflammation, and immune-surveillance evasion mechanisms. Of these, the Hedgehog-GLI (Hh) cell-signaling pathway has been identified as a main molecular contribution into several of the abovementioned functional embryo-malignancy processes. Nonetheless, the systematic study of the regulatory epigenetic and transcriptional mechanisms has remained mostly unexplored, which could identify the interaction networks between specific biomarkers and/or new therapeutic targets in malignant tumor progression and resistance to lung oncologic therapy. In the present work, we aimed to revise the most important up-to-date experimental and clinical findings in biology, embryology and cancer research regarding the Hh pathway. We explore the potential control of the transcriptional-epigenetic programming versus reprogramming mechanisms associated with its Hh-GLI cell signaling pathway members. Last, we present a summary of this information to systematically integrate the Hh signaling pathway to identify and propose novel compound strategies or better oncological therapeutic schemes for lung cancer patients.

Association of chloride intracellular channel 4 and Indian hedgehog proteins with survival of patients with pancreatic ductal adenocarcinoma

Pancreatic cancer is the fourth most common cause of cancer-related mortality. Novel molecular biomarkers need to be identified for personalized medicine and to improve survival. The aim of this study was to examine chloride intracellular channel 4 (CLIC4) and Indian Hedgehog (Ihh) expression in benign and malignant lesions of the pancreas and to examine the eventual association between CLIC4 and Ihh expression, with clinicopathological features and prognosis of pancreatic cancer. A retrospective study of specimens collected from January 2000 to December 2011 at the Department of Pathology of the Second and Third Xiangya Hospitals, Central South University was undertaken to explore this question. Immunohistochemistry of CLIC4 and Ihh was performed with EnVision^™ in 106 pancreatic ductal adenocarcinoma specimens, 35 paracancer samples (2 cm away from the tumour, when possible or available), 55 benign lesions and 13 normal tissue samples. CLIC4 and Ihh expression in pancreatic ductal adenocarcinoma were significantly higher than in paracancer tissue and benign lesions (CLIC4: P = 0.009 and Ihh: P < 0.0001; CLIC4: P = 0.0004 and Ihh: P = 0.0001 respectively). CLIC4 and Ihh expression was negative in normal pancreatic tissues. The expression of CLIC4 and Ihh was associated significantly with tumour grade, lymph node metastasis, tumour invasion and poor overall survival. Thus CLIC4 and Ihh could serve as biological markers for the progression, metastasis and/or invasiveness of pancreatic ductal adenocarcinoma.

Developing Cures: Targeting Ontogenesis in Cancer

Cancer has long been known to histologically resemble developing embryonic tissue. Since this early observation, a mounting body of evidence suggests that cancer mimics or co-opts developmental processes to facilitate tumor initiation and progression. Programs important in both normal ontogenesis and cancer progression broadly fall into three domains: the lineage commitment of pluripotent stem cells, the appropriation of primordial mechanisms of cell motility and invasion, and the influence of multiple aspects of the microenvironment on the parenchyma. In this review we discuss how derangements in these developmental pathways drive cancer progression with a particular focus on how they have emerged as targets of novel treatment strategies.

Human Fibrotic Diseases: Current Challenges in Fibrosis Research

Human fibrotic diseases constitute a major health problem worldwide owing to the large number of affected individuals, the incomplete knowledge of the fibrotic process pathogenesis, the marked heterogeneity in their etiology and clinical manifestations, the absence of appropriate and fully validated biomarkers, and, most importantly, the current void of effective disease-modifying therapeutic agents. The fibrotic disorders encompass a wide spectrum of clinical entities including systemic fibrotic diseases such as systemic sclerosis (SSc), sclerodermatous graft vs. host disease, and nephrogenic systemic fibrosis, as well as numerous organ-specific disorders including radiation-induced fibrosis and cardiac, pulmonary, liver, and kidney fibrosis. Although their causative mechanisms are quite diverse and in several instances have remained elusive, these diseases share the common feature of an uncontrolled and progressive accumulation of fibrotic tissue in affected organs causing their dysfunction and ultimate failure. Despite the remarkable heterogeneity in the etiologic mechanisms responsible for the development of fibrotic diseases and in their clinical manifestations, numerous studies have identified activated myofibroblasts as the common cellular element ultimately responsible for the replacement of normal tissues with nonfunctional fibrotic tissue. Critical signaling cascades, initiated primarily by transforming growth factor-β (TGF-β), but also involving numerous cytokines and signaling molecules which stimulate profibrotic reactions in myofibroblasts, offer potential therapeutic targets. Here, we briefly review the current knowledge of the molecular mechanisms involved in the development of tissue fibrosis and point out some of the most important challenges to research in the fibrotic diseases and to the development of effective therapeutic approaches for this often fatal group of disorders. Efforts to further clarify the complex pathogenetic mechanisms of the fibrotic process should be encouraged to attain the elusive goal of developing effective therapies for these serious, untreatable, and often fatal disorders.

Disruption of KIF3A in patient-derived glioblastoma cells: effects on ciliogenesis, hedgehog sensitivity, and tumorigenesis

KIF3A, a component of the kinesin-2 motor, is necessary for the progression of diverse tumor types. This is partly due to its role in regulating ciliogenesis and cell responsiveness to sonic hedgehog (SHH). Notably, primary cilia have been detected in human glioblastoma multiforme (GBM) tumor biopsies and derived cell lines. Here, we asked whether disrupting KIF3A in GBM cells affected ciliogenesis, in vitro growth and responsiveness to SHH, or tumorigenic behavior in vivo. We used a lentiviral vector to create three patient-derived GBM cell lines expressing a dominant negative, motorless form of Kif3a (dnKif3a). In all unmodified lines, we found that most GBM cells were capable of producing ciliated progeny and that dnKif3a expression in these cells ablated ciliogenesis. Interestingly, unmodified and dnKif3a-expressing cell lines displayed differential sensitivities and pathway activation to SHH and variable tumor-associated survival following mouse xenografts. In one cell line, SHH-induced cell proliferation was prevented in vitro by either expressing dnKif3a or inhibiting SMO signaling using cyclopamine, and the survival times of mice implanted with dnKif3a-expressing cells were increased. In a second line, expression of dnKif3a increased the cells' baseline proliferation while, surprisingly, sensitizing them to SHH-induced cell death. The survival times of mice implanted with these dnKif3a-expressing cells were decreased. Finally, expression of dnKif3a in a third cell line had no effect on cell proliferation, SHH sensitivity, or mouse survival times. These findings indicate that KIF3A is essential for GBM cell ciliogenesis, but its role in modulating GBM cell behavior is highly variable.

Glioblastoma Stem-Like Cells: Characteristics, Microenvironment, and Therapy

Glioblastoma multiforme (GBM), grade IV astrocytoma, is the most fatal malignant primary brain tumor. GBM contains functional subsets of cells called glioblastoma stem-like cells (GSCs), which are radioresistant and chemoresistant and eventually lead to tumor recurrence. Recent studies showed that GSCs reside in particular tumor niches that are necessary to support their behavior. To successfully eradicate GBM growth and recurrence, new strategies selectively targeting GSCs and/or their microenvironmental niche should be designed. In this regard, here we focus on elucidating the molecular mechanisms that govern these GSC properties and on understanding the mechanism of the microenvironmental signals within the tumor mass. Moreover, to overcome the blood–brain barrier, which represents a critical limitation of GBM treatments, a new drug delivery system should be developed. Nanoparticles can be easily modified by different methods to facilitate delivery efficiency of chemotherapeutics, to enhance the accumulation within the tumors, and to promote the capacity for targeting the GSCs. Therefore, nanotechnology has become the most promising approach to GSC-targeting therapy. Additionally, we discussed the future of nanotechnology-based targeted therapy and point out the disadvantages that should be overcome.

Hedgehog/Gli1 signal pathway facilitates proliferation, invasion, and migration of cutaneous SCC through regulating VEGF

Since hedgehog (HH)/Gli1 that contributes to cancer proliferation and metastasis has been masked for decades, the signaling pathway was investigated about its exact role in proliferation and metastasis of cutaneous squamous cell carcinoma (SCC). Sonic hedgehog homolog (Shh), GLI family zinc finger 1 (Gli1), and vascular endothelial growth factor (VEGF) expressions in cutaneous SCC tissues were analyzed with immunohistochemistry, and their correlations with cutaneous SCC patients' prognosis were conducted with Kaplan-Meier curve. Regarding in vitro studies, effects of the HH signaling pathway, and cyclopamine on patched 1 (Ptch1), smoothened/frizzled class receptor (Smo) and VEGF expressions were assessed in A431 cells based on western blot and quantitative real-time polymerase chain reaction (qRT-PCR). Besides, Cell Counting Kit-8 (CCK-8) assay was implemented to evaluate cell proliferation, while wound-healing assay and transwell assay were performed to assess cell migration and invasion, respectively. Mice models were also established to observe effects of Gli1 on tumor diversity and incidence during a period of 20 weeks. Positively expressed VEGF, Gli1, and Shh proteins in cutaneous SCC tissues were correlated with poor survival of patients (P < 0.05). Besides, Gli1 messenger RNA (mRNA) and VEGF mRNA were observed to be significantly over-expressed in A431 cells (P < 0.05), and they were associated with incremental cell proliferation, invasiveness, and migration, which can be reversed by the interference of VEGF siRNA. Furthermore, cyclopamine treatment could induce inhibition of cell proliferation, invasiveness, and migration and suppression of Smo, Gli1, and VEGF expressions. The mice models also confirmed that Gli1 could significantly induce rise of tumor incidence and tumor diversity, while cyclopamine statistically relieved this transformation (P < 0.05). Abnormal activation of the HH signaling pathway plays critical roles in development of cutaneous SCC either in vivo or in vitro.

Overexpression of SCUBE2 Inhibits Proliferation, Migration, and Invasion in Glioma Cells

Signal peptide CUB EGF-like domain-containing protein 2 (SCUBE2), a member of the SCUBE family of proteins, was recently found to play an important role in cancer development. However, little is known regarding its biological function in glioma. In the present study, we investigated the effect of SCUBE2 on glioma and explored its relevant mechanisms. The study showed that SCUBE2 had a low expression in glioma tissue and cell lines. SCUBE2 overexpression inhibited glioma cell proliferation in vitro and in vivo as well as suppressed glioma cell migration and invasion in vitro. Furthermore, we found that the Sonic hedgehog (Shh) signaling pathway was involved in the inhibitory effect of SCUBE2 overexpression on glioma cells. In light of the results obtained from our study, SCUBE2 may be regarded as a potential therapeutic target for glioma.

Loss of Suppressor of Fused in Mid-Corticogenesis Leads to the Expansion of Intermediate Progenitors

Neural progenitors in the embryonic neocortex must be tightly regulated in order to generate the correct number and projection neuron subtypes necessary for the formation of functional neocortical circuits. In this study, we show that the intracellular protein Suppressor of Fused (Sufu) regulates the proliferation of intermediate progenitor (IP) cells at later stages of corticogenesis to affect the number of Cux1+ upper layer neurons in the postnatal neocortex. This correlates with abnormal levels of the repressor form of Gli3 (Gli3R) and the ectopic expression of Patched 1 (Ptch1), a Sonic Hedgehog (Shh) target gene. These studies reveal that the canonical role of Sufu as an inhibitor of Shh signaling is conserved at later stages of corticogenesis and that Sufu plays a crucial role in regulating neuronal number by controlling the cell cycle dynamics of IP cells in the embryonic neocortex.

Eppur Si Muove: Evidence for an External Granular Layer and Possibly Transit Amplification in the Teleostean Cerebellum

The secreted signaling factor Sonic Hedgehog (Shh) acts in the floor plate of the developing vertebrate CNS to promote motoneuron development. In addition, shh has dorsal expression domains in the amniote alar plate (i.e., in isocortex, superior colliculus, and cerebellum). For example, shh expressing Purkinje cells act in transit amplification of external granular layer (EGL) cells of the developing cerebellum. Our previous studies had indicated the presence of an EGL in anamniote zebrafish, but a possible role of shh in the zebrafish cerebellar plate remained elusive. Therefore, we used an existing zebrafish transgenic line Tg(2.4shha-ABC-GFP)sb15; Shkumatava et al., 2004) to show this gene activity and its cellular localization in the larval zebrafish brain. Clearly, GFP expressing cells occur in larval alar zebrafish brain domains, i.e., optic tectum and cerebellum. Analysis of critical cerebellar cell markers on this transgenic background and a PH3 assay for mitotic cells reveals that Purkinje cells and eurydendroid cells are completely non-overlapping postmitotic cell populations. Furthermore, shh-GFP cells never express Zebrin II or parvalbumin, nor calretinin. They are thus neither Purkinje cells nor calretinin positive migrating rhombic lip derived cells. The shh-GFP cells also never correspond to PH3 positive cells of the ventral cerebellar proliferative zone or the upper rhombic lip-derived EGL. From this marker analysis and the location of shh-GFP cells sandwiched between calretinin positive rhombic lip derived cells and parvalbumin positive Purkinje cells, we conclude that shh-GFP expressing cells qualify as previously reported olig2 positive eurydendroid cells, which are homologous to the amniote deep cerebellar nuclei. We confirm this using double transgenic progeny of shh-GFP and olig2-dsRed zebrafish. Thus, these zebrafish eurydendroid cells may have the same role in transit amplification as Purkinje cells do in amniotes.

Neural stem cells, the subventricular zone and radiotherapy: implications for treating glioblastoma

Over the past decade, advances in neuroscience have suggested that neural stem cells resident in specific regions of the adult brain may be involved in development of both primary and recurrent glioblastoma. Neurogenesis and malignant transformation occurs in the subventricular zone adjacent to the lateral ventricles. This region holds promise as a potential target for therapeutic intervention with radiotherapy. However, irradiation of a larger brain volume is not without risk, and significant side effects have been observed. The current literature remains contradictory regarding the efficacy of deliberate intervention with radiation to the subventricular zone. This critical review discusses the connection between neural stem cells and development of glioblastoma, explores the behavior of tumors associated with the subventricular zone, summarizes the discordant literature with respect to the effects of irradiation, and reviews other targeted therapies to this intriguing region.

Morphogenetic and Histogenetic Roles of the Temporal-Spatial Organization of Cell Proliferation in the Vertebrate Corticogenesis as Revealed by Inter-specific Analyses of the Optic Tectum Cortex Development

The central nervous system areas displaying the highest structural and functional complexity correspond to the so called cortices, i.e., concentric alternating neuronal and fibrous layers. Corticogenesis, i.e., the development of the cortical organization, depends on the temporal-spatial organization of several developmental events: (a) the duration of the proliferative phase of the neuroepithelium, (b) the relative duration of symmetric (expansive) versus asymmetric (neuronogenic) sub phases, (c) the spatial organization of each kind of cell division, (e) the time of determination and cell cycle exit and (f) the time of onset of the post-mitotic neuronal migration and (g) the time of onset of the neuronal structural and functional differentiation. The first five events depend on molecular mechanisms that perform a fine tuning of the proliferative activity. Changes in any of them significantly influence the cortical size or volume (tangential expansion and radial thickness), morphology, architecture and also impact on neuritogenesis and synaptogenesis affecting the cortical wiring. This paper integrates information, obtained in several species, on the developmental roles of cell proliferation in the development of the optic tectum (OT) cortex, a multilayered associative area of the dorsal (alar) midbrain. The present review (1) compiles relevant information on the temporal and spatial organization of cell proliferation in different species (fish, amphibians, birds, and mammals), (2) revises the main molecular events involved in the isthmic organizer (IsO) determination and localization, (3) describes how the patterning installed by IsO is translated into spatially organized neural stem cell proliferation (i.e., by means of growth factors, receptors, transcription factors, signaling pathways, etc.) and (4) describes the morpho- and histogenetic effect of a spatially organized cell proliferation in the above mentioned species. A brief section on the OT evolution is also included. This section considers how the differential operation of cell proliferation could explain differences among species.